Is it normal maggots in sushi but my friend ate it

Mmmmm maggots....

Your instinctive reaction was correct; your friend did something very foolish. If what you saw is what I think it was, the restaurant's response to your complaint indicates that either they're ignorant of something that everyone preparing and serving raw fish should know about, or they were flat-out lying and pretending disbelief.

It's likely that what you saw weren't "maggots" which are the larval form of flies, but a parasitical nematode worm commonly called the herring worm (scientific name Anisakis simplex). The natural lifecycle of this worm is complicated and involves shellfish, fish and marine mammals. Humans aren't a natural host for the worm. Sometimes they manage to latch on to the oesophagus after the food is swallowed and the person then coughs it up. But it's possible for a worm to survive all the way to the intestine and to then invade the intestinal wall. The result of this is similar to food poisoning: strong abdominal pain, vomiting and diarrhoea. Normally, the worm dies in a few days because of the body's reaction to it and because it's in an environment it isn't adapted to, but there have been rare cases where the infected person died.

https://www.washington.edu/news/2020/03/19/sushi-parasites-have-increased-283-fold-in-past-40-years/

https://www.verywellhealth.com/anisakis-raw-fish-parasite-1958783

poisoning/news/20170512/sushi-lovers-warned-about-parasites

Well sushi is delicious...

I never would have eaten that (unless I was starving or something). And its not only gross, but its quite possibly health hazardous as well, those things may be parasites. And they could literally see they're there and still choose to eat them?!

Ewwwwww

Most fish have worms. There is a smaller list of fish that might not have worms than fish that have worms. They usually cook to the same color as the fish meat so you have never noticed them.